Logo of the Physikalisch-Technische Bundesanstalt
Into the Future with Metrology - The Challenges of Medical Technology

Measuring system for coronavirus vaccine research

Fast and accurate measurement of the concentration of nanoparticles

PTBnews 1.2022
Especially interesting for

vaccine research

particle analysis

As nanoparticles are smaller than red blood cells, they can be used as a “vehicle” to transport drugs or vaccines. (Photo credits: Adobe Stock / Kateryna_Kon)

In the medical field, nanoparticles represent a source of great hope. They could, for instance, serve as vehicles to help drugs overcome biological obstructions such as the air-blood barrier (in the pulmonary alveoli) and the blood-brain barrier. Researchers are using nanoparticles to try and transport cancer drugs straight to a tumor (drug targeting) or deliver vaccines.

Nanoparticles place great demands on the measuring technology required throughout the chain that stretches from product development to quality control and goes on to product risk assessment. For these tasks, the problem is increasingly not so much measuring the particle size but also measuring the number and concentration of particles.

With this in mind, PTB and LUM GmbH collaborated on a technology transfer project supported by the German Ministry for Economic Affairs and Climate Action to develop the measurement principle of a single-particle light-scattering photometer. With this technology, the distribution and concentration of nano- and microparticles in suspensions and emulsions can be determined with high resolution. Besides exhibiting high accuracy, the system can also be used in a very wide range of applications (for particles from 40 nm to 10 μm), and it is extremely fast, with the ability to analyze up to 10,000 particles per second. The fundamental technology at work here is known as single-particle light scattering (SPLS). Here, the intensity of the light scattered in various directions by each individual nano- or microparticle is measured by the instrument. To get the particles to line up so that they move one by one past the measuring device, the technique of hydrodynamic focusing is applied. In this technique, a so-called sheath flow arranges the particles in the desired direction. The particles then pass as it were single file through the center of the measuring cell. This technique has for years been used very successfully for flow cytometry, where things such as body cells can be counted individually and rapidly.

The new measuring system is capable of analyzing particle suspensions of widely varying compositions without the hardware having to be altered. Even in cases where the starting concentration is very high, the system can determine extremely small differences in size down to the nanometer scale. Both the overall system as well as individual components, such as specific amplifiers and the special optical arrangement, are based on techniques developed by the two partners which have now filed patents for these novel procedures. A global pharmaceuticals company was among the first to take delivery of one of these instruments and will use it for developing a coronavirus vaccine. A renowned German research institution has also acquired this new system.


Martin Hussels
Department 8.3
Biomedical Optics
Phone: +49 30 3481-7628
Opens local program for sending emailmartin.hussels(at)ptb.de